1. Field of the Invention:
The present invention relates to plasticized and stablized poly (vinyl chloride) ["PVC"] compositions, especially those PVC compositions destined for the production of transparent molded articles.
2. Description of the Prior Art
A great number of reference articles relate to PVC-based compositions, plasticized and stabilized against thermal degradation or decomposition caused by either the actual on-stream processing of the composition, or upon subsequent high-temperature utilization.
It is known, for example, according to U.S. Pat. No. 2,711,401, that the use of a mixture of polyol and organic salts of polyvalent metals enables retardation of the yellowing of molded articles subjected to heat.
Furthermore, according to U.S. Pats. Nos. 3,003,998, 3,003,999 and 3,004,000, non-toxic stabilizers have been found which can be used for the packaging of food products, and which are based on a mixture of fatty acid salts of magnesium, zinc or calcium with a polyol. However, the transparency demanded for certain applications canot be obtained with these mixtures.
French Pat. No. 1,435,882 proposes the association of an organic salt of an alkali metal and a ketoacetic ester or dehydroacetic acid. However, the resulting stabilization is far from satisfactory.